Want To See Comet PANSTARRS? We Got Maps!

This is the big week so many of us in the northern hemisphere have been waiting for. Comet C/2011 L4 PANSTARRS, which has put on a splendid show in the southern hemisphere, finally comes to a sky near you.

Sky watchers in Australia report it looks like a fuzzy star as bright as those in the Big Dipper with a short stub of a tail visible to the naked eye. The comet should brighten further as it wings its way sunward. Closest approach to the sun happens on March 10 at a distance of 28 million miles or about 8 million miles closer than the planet Mercury.

If you live near the equator you can already hunt for PANSTARRS. It will be out tonight March 4 very low in the west-southwest sky 25 minutes after sundown. Depending on your latitude, the comet will make its first appearance over the U.S. March 6-8 assuming the sky at your location is transparent and haze-free.

As described in an earlier blog, PANSTARRS’ low altitude presents a few challenges. Approaching clouds and general haziness near the horizon can make it a tricky to find. The maps should help as will a pair of binoculars. Use them to sweep just above the western horizon later this week to find the comet.

Comet PANSTARRS will be visible tonight through about March 19 for sky watchers living near the equator. Map is drawn for Singapore. All maps created with Chris Marriott’s SkyMap software

As the nights pass, PANSTARRS rises higher in the sky and becomes easier to spot for northern hemisphere observers while disappearing from view in the south. On the 12th, a thin lunar crescent will shine just to the right of the comet. Not only will it make finding this fuzzy visitor easy-peasy, but you’ll have the opportunity to make a beautiful photograph.

Comet PANSTARRS map for the southern U.S. March 6-21. Time shown is about 25 minutes after sunset facing west. Map is drawn for Phoenix, Ariz.

The maps shows the arc of the comet across the western sky in the coming two weeks for three different latitudes. Along the bottom of each map is the comet’s altitude in degrees for the four labeled dates. The sun, which is below the horizon, but whose bright glow you’ll see above its setting point, will help you determine exactly in what direction to look.

One of your best observing tools and the one closest at hand (pun intended) is your hand. Photo: Bob King

A word about altitude. Astronomers measure it in degrees. One degree is the width of your little finger held at arm’s length against the sky. Believe it or not, this covers two full moon’s worth of sky. Three fingers at arm’s length equals 5 degrees or the separation between the two stars at the end of the bowl of the Big Dipper. A fist is 10 degrees.

The northern U.S. is favored for this leg of the comet’s journey. Notice how the comet arcs up higher in the sky compared to the southern U.S. and especially the equator. Map drawn for Duluth, Minn. The comet will remain visible for many weeks. Earth is closest to PANSTARRS on March 5 at 102 million miles.

To find PANSTARRS, locate it on the map for a particular date, note its approximate altitude and relation to where the sun set and look in that direction. Assuming your sky to the west is wide open and clear, you should see a comet staring back. If not, sweep back and forth in the area with binoculars. Sound good? Great – now have at it!

I also have a question about Sirius – at least I think it was Sirius 🙂 Last night around midnight (europe-time) I saw this star in the south-west – it looked like a ‘pulsating’ star, because of the changing colours – I tried to take some photo’s, and got some ‘weird’ pictures – according to your explanation (that I read just now), it must have been Sirius – I think it’s time for me to buy a telescope :-)greetings from Belgium – Mia

Hi Mia. Yes it was Sirius. It’s the brightest star in night sky (and brightest object, after Moon and some planets). It has changing color because it’s bright and low, especially at north latitudes like yours, and light from low stars goes through lots of atmosphere, which refracts color in a continuously changing way, especially if air has turbulence. Getting a telescope wouldn’t change things – we can’t see details of a star with amateur telescopes. Although for sure, a telescope is a very useful tool to see many things.

Thanx Bob for the guide and sharing great photos. Our local forecast here in Trieste is clouds and rain covering exactly all the period of visibility of the comet, but I hope for some clearing. We just had a few days of both great seeing and transparency, which is very rare here, for instance we saw a very contrasted Jupiter in scope in daylight, including the great red spot. I knew the comet was in the sky during some day hours and tried to catch it with scope, but, as I guessed, I couldn’t, as it’s too faint to be seen at daylight. I catched objects in daylight up to magnitude 1-2, besides the comet is a diffuse object. Well, to consolate myself in that moment I got my first pic of the ISS at day. I can see the solar panels…

Hi Shari,
There is only one good comet for viewing right now – that’s Comet PANSTARRS. Use the map in the blog and you should be able to spot it starting about tomorrow very low in the western sky about 25 minutes after sunset. Look a little left to where the bright twilight glow sits on the horizon.

my thanks to Bob and to Giorgio, for their reply. yesterday-evening would have been a great time to observe and look for Panstarrs, but the weather changed and even as I write this, the sky is covered with clouds, probably for the entire day. I can only hope for a clearer evening ..

I finally found PanSTARRS tonight. My first comet ever! I’m still very excited. It was only visible through my binos due to haze and dust. I did get a photo of it as well, however it is poor due to not setting up as I would’ve liked to because of the wind. Conditions should be better tomoorow and I can’t wait.

Sandra,
The sun sets for you at 7:08 p.m. this evening. You can start looking for the comet around 7:30 p.m. low in the west-southwest sky. Be sure to bring binoculars and use them to sweep slowly above the horizon in that direction. The comet will be 6 degrees high at 7:30 p.m. and visible until about 7:55 p.m. getting lower all the time.

I’ve been peeking 3 nights in a row just in case it was my only chance to see it (clouds predicted most of next week), but to no avail, darn it! However, I’m at 46N. I think my selected western horizon is unobstructed by our rolling hills … enough so …. time may or may not tell. Thank you for the diagrams. They have helped. Do I understand correctly that it simply “sets” like the sun in the 30 minutes of potential viewing post sunset? Has anybody in the northern US spotted it that you are aware of?

I tried to view comet March 10th right after sunset with a small telescope and binoculars with no success. Right along the sunset line were beautiful pink/orange and gray clouds. Is that why I couldn’t see it??

Hi Cynthia,
Sorry to hear you didn’t spot. It could have been the clouds or you could have looked too early if you were out right after sunset. Best time is about 25 minutes after sunset when the comet will be a little more than 3 fingers (held horizontally) above the west-southwest horizon.

Your charts are useful, but even more useful would be charts including the elevation of the moon also, or just tabular lists of elevation or moon-set, comet-set, and the horizontal separation of the two, relative to local sunset for various days and latitudes. NASA chart is misleading showing the comet always higher than the moon.

Hi Bob,
Like you I was surprised at inaccuracy of the NASA chart. When working on my own chart, it took a great deal of time plotting the comet’s position while keeping the sun’s altitude below the horizon constant. Especially for 3 latitude bands. Moonset and comet elevations are a great idea but vary significantly depending on latitude. I like your suggestions and will incorporate some aspect of them when I create the next set of charts.

How much trouble is it to make a computing box that finds the time and position of sunset for a given day and latitude, and then uses that time to find to find the position of the moon observed from that latitude at that time? I would think that someone has already worked out those formulas. If that is available elsewhere then your computation box for the observed position of the comet for a time/date and latitude is whats needed.

Hi Bob,
The “computing box” you talk about is essentially a planetarium program like Stellarium which can be downloaded for free. The other day I included a description in my blog on how to show Comet PANSTARRS (or any other currently observable comet) in Stellarium for anyone, anywhere, any time of day or night. As for using the moon to locate the comet, we only had two days for that. By day 3, the moon had moved too far from the comet to be useful. It was a lucky coincidence that the two were near one another when the comet was near its brightest. My maps were intended for broad bands of latitude. One last note: you can always find sunrise/sunset/moonrise/moonset for any location by clicking on a link I’ve provided for that purpose on the links list to the right of the blog entry.